Tax return and allowance for year of death

Dazed_and_C0nfused

The request to transfer the allowance from mum to dad was part of each year’s tax return 

I think you need to fully understand this as well.

There are only two situations where this could apply,.

1.  Your mum applied for Marriage Allowance, giving your dad a tax reducer of ~£250/year.

2.  She was entitled to a share of the Married Couple's Allowance (known as a form 18 election) and didn't need it all so could transfer the surplus back to him (a 575 election).

Married Couple's Allowance is worth far more in tax savings terms, up to ~£1k in the current year compared to just £252 for Marriage Allowance.